Buggy code:
protected AbstractSAXParser ( XMLParserConfiguration config ) { } public void startDocument ( XMLLocator locator , String encoding , NamespaceContext namespaceContext , Augmentations augs ) throws XNIException { } public void xmlDecl ( String version , String encoding , String standalone , Augmentations augs ) throws XNIException { } public void doctypeDecl ( String rootElement , String publicId , String systemId , Augmentations augs ) throws XNIException { } public void startGeneralEntity ( String name , XMLResourceIdentifier identifier , String encoding , Augmentations augs ) throws XNIException { } public void endGeneralEntity ( String name , Augmentations augs ) throws XNIException { } public void startElement ( QName element , XMLAttributes attributes , Augmentations augs ) throws XNIException { } public void characters ( XMLString text , Augmentations augs ) throws XNIException { } public void ignorableWhitespace ( XMLString text , Augmentations augs ) throws XNIException { } public void endElement ( QName element , Augmentations augs ) throws XNIException { } public void startCDATA ( Augmentations augs ) throws XNIException { } public void endCDATA ( Augmentations augs ) throws XNIException { } public void comment ( XMLString text , Augmentations augs ) throws XNIException { } public void processingInstruction ( String target , XMLString data , Augmentations augs ) throws XNIException { } public void endDocument ( Augmentations augs ) throws XNIException { } public void startExternalSubset ( XMLResourceIdentifier identifier , Augmentations augs ) throws XNIException { } public void endExternalSubset ( Augmentations augs ) throws XNIException { } public void startParameterEntity ( String name , XMLResourceIdentifier identifier , String encoding , Augmentations augs ) throws XNIException { } public void endParameterEntity ( String name , Augmentations augs ) throws XNIException { } public void elementDecl ( String name , String contentModel , Augmentations augs ) throws XNIException { } public void attributeDecl ( String elementName , String attributeName , String type , String [ ] enumeration , String defaultType , XMLString defaultValue , XMLString nonNormalizedDefaultValue , Augmentations augs ) throws XNIException { } public void internalEntityDecl ( String name , XMLString text , XMLString nonNormalizedText , Augmentations augs ) throws XNIException { } public void externalEntityDecl ( String name , XMLResourceIdentifier identifier , Augmentations augs ) throws XNIException { } public void unparsedEntityDecl ( String name , XMLResourceIdentifier identifier , String notation , Augmentations augs ) throws XNIException { } public void notationDecl ( String name , XMLResourceIdentifier identifier , Augmentations augs ) throws XNIException { } public void endDTD ( Augmentations augs ) throws XNIException { } public void parse ( String systemId ) throws IOException , SAXException { } public void parse ( InputSource inputSource ) throws IOException , SAXException { } public void setEntityResolver ( EntityResolver resolver ) { } public EntityResolver getEntityResolver ( ) { } public void setErrorHandler ( ErrorHandler errorHandler ) { } public ErrorHandler getErrorHandler ( ) { } public void setLocale ( Locale locale ) throws SAXException { } public void setDTDHandler ( DTDHandler dtdHandler ) { } public void setDocumentHandler ( DocumentHandler documentHandler ) { } public void setContentHandler ( ContentHandler contentHandler ) { } public ContentHandler getContentHandler ( ) { } public DTDHandler getDTDHandler ( ) { } public void setFeature ( String featureId , boolean state ) throws SAXNotRecognizedException , SAXNotSupportedException { } public boolean getFeature ( String featureId ) throws SAXNotRecognizedException , SAXNotSupportedException { try { if ( featureId . startsWith ( SAX_FEATURE_PREFIX ) ) { final int suffixLength = ( featureId . length ( ) ) - ( SAX_FEATURE_PREFIX . length ( ) ) ; if ( ( suffixLength == ( NAMESPACE_PREFIXES_FEATURE . length ( ) ) ) && ( featureId . endsWith ( NAMESPACE_PREFIXES_FEATURE ) ) ) { boolean state = fConfiguration . getFeature ( featureId ) ; return state ; } if ( ( suffixLength == ( STRING_INTERNING_FEATURE . length ( ) ) ) && ( featureId . endsWith ( STRING_INTERNING_FEATURE ) ) ) { return true ; } if ( ( suffixLength == ( IS_STANDALONE_FEATURE . length ( ) ) ) && ( featureId . endsWith ( IS_STANDALONE_FEATURE ) ) ) { return fStandalone ; } if ( ( suffixLength == ( XML_11_FEATURE . length ( ) ) ) && ( featureId . endsWith ( XML_11_FEATURE ) ) ) { <START_BUG> return ( fConfiguration ) instanceof XML11Configuration ; <END_BUG> } if ( ( suffixLength == ( LEXICAL_HANDLER_PARAMETER_ENTITIES_FEATURE . length ( ) ) ) && ( featureId . endsWith ( LEXICAL_HANDLER_PARAMETER_ENTITIES_FEATURE ) ) ) { return fLexicalHandlerParameterEntities ; } if ( ( suffixLength == ( RESOLVE_DTD_URIS_FEATURE . length ( ) ) ) && ( featureId . endsWith ( RESOLVE_DTD_URIS_FEATURE ) ) ) { return fResolveDTDURIs ; } if ( ( suffixLength == ( XMLNS_URIS_FEATURE . length ( ) ) ) && ( featureId . endsWith ( XMLNS_URIS_FEATURE ) ) ) { return fXMLNSURIs ; } if ( ( suffixLength == ( UNICODE_NORMALIZATION_CHECKING_FEATURE . length ( ) ) ) && ( featureId . endsWith ( UNICODE_NORMALIZATION_CHECKING_FEATURE ) ) ) { return false ; } if ( ( ( suffixLength == ( USE_ATTRIBUTES2_FEATURE . length ( ) ) ) && ( featureId . endsWith ( USE_ATTRIBUTES2_FEATURE ) ) ) || ( ( suffixLength == ( USE_LOCATOR2_FEATURE . length ( ) ) ) && ( featureId . endsWith ( USE_LOCATOR2_FEATURE ) ) ) ) { return false ; } } return fConfiguration . getFeature ( featureId ) ; } catch ( XMLConfigurationException e ) { String identifier = e . getIdentifier ( ) ; if ( ( e . getType ( ) ) == ( XMLConfigurationException . NOT_RECOGNIZED ) ) { throw new SAXNotRecognizedException ( SAXMessageFormatter . formatMessage ( fConfiguration . getLocale ( ) , "feature-not-recognized" , new Object [ ] { identifier } ) ) ; } else { throw new SAXNotSupportedException ( SAXMessageFormatter . formatMessage ( fConfiguration . getLocale ( ) , "feature-not-supported" , new Object [ ] { identifier } ) ) ; } } } public void setProperty ( String propertyId , Object value ) throws SAXNotRecognizedException , SAXNotSupportedException { }

Fix:
return ( fConfiguration ) instanceof XML11Configurable ;